He was the original Merlin in Camelot. He had the first scene with Arthur and then the long monologue over Follow Me, in which he warns Arthur of the traps in his future. Also, I remember reading one of his interviews. Apparently Walter Kerr
had raved about his performance in an off Broadway show (maybe Look After Lulu) but did not compliment the other actors. In the interview, he tells how embarrassed he was to face them after the review. Always an actor with integrity.